Reference may be made to J. Am. Chem. Soc., 116, 1054–1062 (1994), by Gellman et al, wherein the β- and γ-amino acids were postulated to fold in the same manner as α-amino acids through intramolecular hydrogen bonding.
In 1996, two groups of scientists, one led by Seebach et al and another by Gellman et al reported the first synthesis of β-peptides showing well-defined secondary structures. Reference may be made to Helv. Chim. Acta 79, 913–941 and 2043–2066 (1996), wherein it was the fist group worked on the synthesis of β-hexapeptide consisting of acyclic β-amino acid monomers and explored for the secondary structures along with effects of residue variation on the secondary structures.
Reference may be made to J. Am. Chem. Soc., 118, 13071–72 (1996), wherein Gellman group worked on the synthesis of β-peptides containing a cyclohexane 1,2-amino acid (ACHC) as β-amino acid monomer to derive a 14-helical structure. Reference may further be made to Nature 387, 381 (1997), wherein cyclopentane amino acid (ACPC) gave 12-helical structure.
Reference may be made to Helv. Chim. Acta 81, 932 (1998), wherein Seebach's group worked on β2–β3 mixed hexapeptide which exhibited a 12/10/12 helix (10/12 helix) while reference may be made to Helv. Chim. Acta. 81, 2218–2243(1998), wherein β3,3, β2,2 amino acids and their β-peptides were prepared, while β3,3 have shown 8-helix.
Reference may be made to Angew. Chem. Int. Ed , 41, 230–253 (2002); Chem. Rev. 102, 491–514 (2002); Chem. Eur. J., 8, 4366–4376 (2002), which reviewed about a new class of ‘sugar amino acids’ wherein both the acid and amine components are installed on the carbohydrate frame and a variety of α,β,γ,δ,-sugar amino acids were prepared and converted into the corresponding peptides of a variety of secondary structures and biological activities.